Hey, I 've long perused this board, and I now have a reason to sign up- I have a question.

When I throw a right knee (Thai Style, no clinch), if I do it with any real speed or force- either in the air or into a bag, it hurts right behind my knee in the hinging part of the joint. It's not a muscle pain, I think it's a tendon or ligament thing, not sure. It happens when I go fairly fast and/or high, so I wonder if it might be a flexibility thing?

I was researching it, and the closest description I could find was something called runner's knee. But I don't really run much, and I don't feel it when I do. Just when throwing the knee.